1. Field of the Invention
The present invention relates to a printing control apparatus and, more particularly, to an improved printing control apparatus that allows a printer to develop data prepared by a computer or like equipment as bit image data.
2. Description of Related Art
Some printers conventionally utilize a page memory allocated in a semiconductor storage device of the printing control apparatus attached thereto, the page memory having a capacity of one-page bit image data to be printed. Print command data such as bit image data, character codes and other data sent from an external computer or the like are developed as print bit image data in the page memory. After such data development, the print station of the printer is started. The developed print bit image data are then output to the print station for one-page printing.
However, recent improvements in the resolution and image quality of printers have tremendously boosted the amount of print bit image data to be printed per page. This trend has not only increased the prices of the printers because of their more expensive semiconductor storage devices incorporated, it has also produced a number of problems including higher power dissipation, higher electric capacity required to drive the semiconductor device and a limit to the amount of data handled by a CPU. These constraints have become so restrictive that some printers of high performance specifications are almost impossible to build at a reasonable cost. In any case, semiconductor storage devices are required to be larger than ever in capacity to execute large amounts of print output.
For example, A4-size printout by conventional monochromatic laser printers generally requires one-bit data per pixel. When their resolution is about 12 pixel/mm, such laser printers need to have a semiconductor storage device with a capacity of about one megabyte in order to retain one A4 page of bit image data. Where printing requirements are dramatically raised, e.g., where the output size is A0 and the resolution is 12 pixel/mm, with 16.70 million colors (24 bits/pixel: yellow 8 bits, magenta 8 bits, cyan 8 bits; or 36 bits/pixel: yellow 8 bits, magenta 8 bits, cyan 8 bits, black 8 bits) assigned per pixel, a memory capacity of at least 500 megabytes is required to accommodate just one page of print bit image data. The memory requirement has led to a drastic hike in equipment cost, making it virtually impossible to build economically feasible printers.